Mobile Voltammetric Analysis

1. A mobile voltammetric analysis system for conducting electrochemical analysis of an analyte, the system comprising: a mobile computing device; a voltammetric cell for receiving a sample of the analyte, and comprising first and second electrodes; and a circuit configuration comprising a resistor and a capacitor for connecting the mobile computing device to the voltammetric cell, wherein the mobile computing device comprises: a microprocessor; one or more memory components comprising a program and data store accessible to the microprocessor; and an audio interface comprising an audio signal output having first and second channels and an audio signal input, which is operable under control of the microprocessor, wherein the audio interface is connectible, in use, to the voltammetric cell with the first channel of the audio signal output being connected to the first electrode, the second channel of the audio signal output being connected to the second electrode via the resistor, and the audio signal input being connected to the second electrode via the capacitor; and the program and data store containing instructions which, when executed by the microprocessor, cause the mobile computing device to implement steps of: generating an output voltage waveform between the first and second channels of the audio signal output, the output voltage waveform comprising a time-varying voltammetric driving potential and an AC perturbation; simultaneously with generating the output voltage waveform, capturing an input voltage waveform received at the audio signal input; and recording within the data store the input voltage waveform as a voltammetric response waveform indicative of a characteristic of the analyte.

2. The system of claim 1 wherein the instructions cause the mobile computing device to generate the output voltage waveform by: generating a first waveform comprising the voltammetric driving waveform; generating a second waveform comprising an inverse of the voltammetric driving waveform; superimposing the AC perturbation to one of the first and second waveforms; and applying the first waveform to the first channel of the audio signal output, and the second waveform to the second channel of the audio signal output.

3. The system of claim 1 wherein the instructions cause the mobile computing device to generate the output voltage waveform in which the voltammetric driving potential is a triangle wave.

4. The system of claim 1 wherein the resistor has a value in the range 47Ω to 4.7 kΩ, more particularly in the range 68Ω to 390Ω, and more particularly around 100Ω.

5. The system of claim 1 wherein a frequency of the AC perturbation is in the range 50 Hz to 500 Hz, more particularly in the range 100 Hz to 400 Hz, and more particularly in the range of around 200 Hz to around 300 Hz.

6. The system of claim 5 wherein the frequency of the AC perturbation is not 50 Hz, or any multiple of 50 Hz, and/or is not 60 Hz, or any multiple of 60 Hz.

7. The system of claim 1 wherein an amplitude of the AC perturbation, relative to a peak output voltage, is in the range 0.7 percent to 7 percent, and more particularly around 3 percent to around 5 percent.

8. A method of AC voltammetric analysis of an analyte in a voltammetric cell, the method comprising: providing a mobile voltammetric analysis system according to claim 1 ; connecting, to the voltammetric cell, the mobile computing device using the circuit configuration such that the first channel of the audio signal output is connected to the first electrode of the voltammetric cell, the second channel of the audio signal output is connected to the second electrode of the voltammetric cell via the resistor, and the audio signal input is connected to the second electrode of the voltammetric cell via the capacitor; the mobile computing device: generating an output voltage waveform between the first and second channels of the audio signal output, the output voltage waveform comprising a time-varying voltammetric driving potential and an AC perturbation; simultaneously with generating the output voltage waveform, capturing an input voltage waveform received at the audio signal input; recording the input voltage waveform as a voltammetric response waveform within the data store; and performing a second harmonic analysis of the voltammetric response waveform to obtain a corresponding voltammogram indicative of a characteristic of the analyte.

9. The method of claim 8 wherein performing the second harmonic analysis comprises filtering a second harmonic waveform from the AC perturbation, and obtaining the voltammogram as an envelope of the filtered second harmonic waveform.

10. A computer program product comprising a computer-readable medium upon which instructions are recorded that are executable by a mobile computing device connectable to a voltammetric cell via a circuit configuration, the voltammetric cell for receiving a sample of the analyte, and comprising first and second electrodes, the circuit configuration comprising a resistor and a capacitor for connecting the mobile computing device to the voltammetric cell, and the mobile computing device having a microprocessor, one or more memory components comprising a program and data store accessible to the microprocessor, and an audio interface which comprises an audio signal output having first and second channels and an audio signal input, wherein the audio interface is operable under control of the microprocessor, and is connectible, in use, to the voltammetric cell with the first channel of the audio signal output being connected to the first electrode, the second channel of the audio signal output being connected to the second electrode via the resistor, and the audio signal input being connected to the second electrode via the capacitor, the instructions being configured such that, when executed by the microprocessor, the mobile computing device is caused to implement steps of: generating an output voltage waveform between the first and second channels of the audio signal output, the output voltage waveform comprising a time-varying voltammetric driving potential and an AC perturbation; simultaneously with generating the output voltage waveform, capturing an input voltage waveform received at the audio signal input; and recording within the data store the input voltage waveform as a voltammetric response waveform indicative of a characteristic of the analyte.

11. The system of claim 1 wherein the characteristic of the analyte is a concentration of the analyte.

12. The method of claim 8 wherein the characteristic of the analyte is a concentration of the analyte.